Audio between Raspberry Pi2 and EHS6 in call | Telit Cinterion IoT Developer Community
April 2, 2020 - 12:01am, 856 views
I refer you to ask about a challenge I am having with the Gemalto EHS6 module. I am using a Raspberry Pi 2 with Ubuntu, to automate calls and SMS messaging using Python, my goal is to play a pre-recorded audio on calls and to be heard on the destination phone. So far, the transmission seems to be working, however the only thing you hear is noise during the call, there are no features to identify the recording, so I am having doubts if I am using the correct pins of the Gemalto GPIO.
From the Raspberry I am extracting the audio through PWM, and I am connecting it to the Gemalto GPIO21, which corresponds to RXDDAI, additionally I am linking the grounds between the Raspberry and the Gemalto.
Currently I have doubts about the GPIO22 (TFSDAI) and GPIO23 (SCLK) pins. Should they be used? Or are they only used to transmit from Gemalto to Raspberry?
Maybe if someone has done something similar, could you explain how you have done it to guide me a bit. I was guiding myself based on the following topic on this website: https://iot-developer.thalesgroup.com/tutorial/audio-codec-board-2g3g-terminal-pcm-interface
Thank you very much, greetings!
This module has a digital audio interface (DAI). The DAI can be used to connect audio devices capable of pulse code modulation (PCM).
In the example you refer to there is an external codec connecte to DAI interface which convetrs the digital signal to analog voice.
I don't know if you don't need any additional hardware between Pi and the module.
Anyway if Raspberri Pi has DAI interface you need all the lines to be connected.
Please also see 'Digital Audio Interface' chapter in the module's hardware interface description which you can find here: https://iot-developer.thalesgroup.com/documentation/download-documentati...